[Elecraft] K2, PSK31 & microphone

[Matt Osborn]

I'm using Ham Radio Deluxe/PSK31 Deluxe software which handles the
PTT, but I still need to connect from the sound card to the K2's
microphone jack.

I have the Proset-K2 headset that has an 8 pin adapter that accepts
the monophonic Proset-K2 microphone plug.  I would like to use an
audio ground loop isolator to connect the sound card audio out to the
Proset-K2 adapter microphone plug.

However, when I installed the Proset-K2, I had to install a 5.6K
resister between 5V (pin 6) to the AF (pin 1)  on the back of 8 pin
microphone adapter on the K2.

I don't know the purpose of this resister; I assumed it was just a
pull up.  Is it safe to leave this resister in place?